Effects and metabolism of fumarate in the perfused rat heart. A 13C mass isotopomer study

1997 ◽  
Vol 272 (1) ◽  
pp. E74-E82 ◽  
Author(s):  
A. Laplante ◽  
G. Vincent ◽  
M. Poirier ◽  
C. Des Rosiers
Keyword(s):  
Contractile Function ◽  
Gas Chromatography Mass Spectrometry ◽  
Perfused Rat Heart ◽  
Relative Contribution ◽  
Rat Hearts ◽  
Isotopomer Analysis ◽  
Cardioprotective Effects ◽  
Cellular Necrosis ◽  
13C Isotopomer Analysis ◽  
Reductive Pathway

The cardioprotective effects of fumarate have been linked to its metabolism to succinate through both oxidative and reductive pathways. To date, the relative contribution of these pathways is a subject of controversy. To address this question, we designed a protocol with 13C substrates and took advantage of 13C isotopomer analysis by gas chromatography-mass spectrometry. Rat hearts were perfused with 11 mM glucose, 1 mM lactate, 0.2 mM pyruvate, 0.2 mM [1-13C]octanoate, and 0.04 or 0.4 mM [U-13C4]fumarate. On reoxygenation after 40 min of severe hypoxia, hearts perfused with 0.4 mM fumarate showed a better recovery of contractile function and released less lactate dehydrogenase (an index of cellular necrosis) than those perfused with 0.04 mM fumarate. The 13C data showed that, in hypoxic hearts, fumarate conversion to succinate occurred only through reduction, although it accounted for only 16% of total succinate release. Most of the succinate was formed through the oxidation of alpha-ketoglutarate or its precursors (50 +/- 5%) and by another yet-unidentified pathway (34 +/- 4%). These data show that, in a model of hypoxia-reoxygenation, the cardioprotective effects of fumarate were associated with its predominant metabolism to succinate through the reductive pathway.

scholarly journals Triidothyronine and epinephrine rapidly modify myocardial substrate selection: a 13C isotopomer analysis

2001 ◽  
Vol 281 (5) ◽  
pp. E983-E990 ◽  
Author(s):  
Julia J. Krueger ◽  
Xue-Han Ning ◽  
Barisa M. Argo ◽  
Outi Hyyti ◽  
Michael A. Portman
Keyword(s):  
Direct Action ◽  
Tricarboxylic Acid Cycle ◽  
Substrate Selection ◽  
Acetoacetic Acid ◽  
Rat Hearts ◽  
Isotopomer Analysis ◽  
Myocardial Substrate ◽  
13C Isotopomer Analysis ◽  
High Work ◽  
C Nmr

Triiodothyronine (T3) exerts direct action on myocardial oxygen consumption (MV˙o 2), although its immediate effects on substrate metabolism have not been elucidated. The hypothesis, that T3 regulates substrate selection and flux, was tested in isovolumic rat hearts under four conditions: control, T3 (10 nM), epinephrine (Epi), and T3 and Epi (TE). Hearts were perfused with [1,3-13C]acetoacetic acid (AA, 0.17 mM),l-[3-13C]lactic acid (LAC, 1.2 mM), U-13C-labeled long-chain free fatty acids (FFA, 0.35 mM), and unlabeled d-glucose (5.5 mM) for 30 min. Fractional acetyl-CoA contribution to the tricarboxylic acid cycle (Fc) per substrate was determined using 13C NMR and isotopomer analysis. Oxidative fluxes were calculated using Fc, the respiratory quotient, and MV˙o 2. T3increased ( P < 0.05) FcFFA, decreased FcLAC, and increased absolute FFA oxidation from 0.58 ± 0.03 to 0.68 ± 0.03 μmol · min−1 · g dry wt−1( P < 0.05). Epi decreased FcFFA and FcAA, although FFA flux increased from 0.58 ± 0.03 to 0.75 ± 0.09 μmol · min−1 · g dry wt−1. T3 moderated the change in FcFFA induced by Epi. In summary, T3 exerts direct action on substrate pathways and enhances FFA selection and oxidation, although the Epi effect dominates at a high work state.

Comparative cardioprotective effects of cromakalim and diltiazem in ischemic hypertrophied rat hearts

1996 ◽  
Vol 270 (1) ◽  
pp. H174-H182
Author(s):  
G. J. Grover ◽  
S. Dzwonczyk ◽  
T. M. Monticello
Keyword(s):  
Cardiac Hypertrophy ◽  
Contractile Function ◽  
Heart Weight ◽  
Dependent Manner ◽  
Sprague Dawley ◽  
Concentration Dependent Manner ◽  
Rat Hearts ◽  
Cardioprotective Effects ◽  
Ldh Release ◽  
Wistar Kyoto

Previous studies have indicated that alterations in cardiac ATP-sensitive potassium channels (KATP) can occur with cardiac hypertrophy. The goal of this study was to determine the effect of cardiac hypertrophy in spontaneously hypertensive rats (SHR) on the response to the cardioprotective agents diltiazem and cromakalim. Isolated rat hearts from 14-wk-old SHR, normotensive heterozygote Wistar-Kyoto (WKY), and Sprague-Dawley (SD) strains were subjected to 25 min of global ischemia and 30 min of reperfusion in the presence of vehicle (3-30 microM cromakalim or 0.1-1.0 microM diltiazem). SHR had heart weight-to-body weight ratios 40-50% greater than age-matched SD or WKY. Both diltiazem and cromakalim increased reperfusion contractile function in a concentration-dependent manner in SD rats as previously reported. Cromakalim and diltiazem caused similar improvements in reperfusion function in WKY rats and SHR. Cumulative lactate dehydrogenase (LDH) release during reperfusion was similar for vehicle-treated SD, WKY, or SHR hearts. LDH release was significantly attenuated by cromakalim and dilitiazem at all concentrations tested in SD and WKY hearts, whereas LDH release was not attenuated in SHR hearts by any concentration of cromakalim or diltiazem tested. Morphological assessment of hearts by light microscopy indicated that the severity and distribution of myocardial lesions were not affected by cromakalim in SHR hearts, compared with vehicle-treated SHR, supporting the LDH data. These results suggest that in SHR hearts, cromakalim and dilitiazan may exert much of their cardioprotective effects on the population of myocytes that are not irreversibly damaged.

Preconditioning accelerates contracture and ATP depletion in blood-perfused rat hearts

1995 ◽  
Vol 269 (4) ◽  
pp. H1415-H1420 ◽  
Author(s):  
K. G. Kolocassides ◽  
M. Galinanes ◽  
D. J. Hearse
Keyword(s):  
Rat Heart ◽  
Contractile Function ◽  
Study Groups ◽  
Atp Depletion ◽  
Perfused Rat Heart ◽  
Ischemic Contracture ◽  
Isolated Hearts ◽  
Time To Peak ◽  
Rat Hearts ◽  
Perfused Rat Hearts

We investigated the effect of preconditioning on the ischemia-induced depletion of ATP in the blood-perfused rat heart. Isolated hearts (n = 5/group) were aerobically perfused with whole blood from a support rat and subjected to zero-flow global ischemia (37 degrees C) for periods up to 35 min. Frozen hearts were taken for metabolic analysis. Ischemic contracture was assessed with an isovolumic intraventricular balloon. The study groups were 1) control (C) with unprotected ischemia, 2) preconditioning (PC; 2 cycles of 3-min ischemia/3-min reperfusion), and 3) cardioplegia (CP; St. Thomas') before ischemia. Preconditioning accelerated, whereas cardioplegia delayed, ischemic contracture (time to peak contracture: PC = 8.1 +/- 0.3 and CP = 25.1 +/- 0.2 min vs. C = 15.6 +/- 0.3 min, P < 0.05). The ischemia-induced decline in ATP was delayed by cardioplegia but accelerated by preconditioning (P < 0.05). In a parallel study, preconditioning and cardioplegia protected postischemic contractile function to a similar extent. Thus, in the blood-perfused rat heart, preconditioning accelerated ischemic contracture and depletion of ATP. In contrast, cardioplegia slowed ischemic contracture and ATP depletion.

scholarly journals Reverse flux through cardiac NADP+-isocitrate dehydrogenase under normoxia and ischemia

2002 ◽  
Vol 283 (4) ◽  
pp. H1505-H1514 ◽  
Author(s):  
Blandine Comte ◽  
Geneviève Vincent ◽  
Bertrand Bouchard ◽  
Mohamed Benderdour ◽  
Christine Des Rosiers
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Contractile Function ◽  
Low Flow ◽  
Reverse Direction ◽  
Long Chain Fatty Acids ◽  
Rat Hearts ◽  
Isotopomer Analysis ◽  
Fine Regulation

Little is known about the role of mitochondrial NADP+-isocitrate dehydrogenase (NADP+-ICDH) in the heart, where this enzyme shows its highest expression and activity. We tested the hypothesis that in the heart, NADP+-ICDH operates in the reverse direction of the citric acid cycle (CAC) and thereby may contribute to the fine regulation of CAC activity (Sazanov and Jackson, FEBS Lett344: 109–116, 1994). We documented a reverse flux through this enzyme in rat hearts perfused with the medium-chain fatty acid octanoate using [U-13C5]glutamate and mass isotopomer analysis of tissue citrate (Comte et al., J Biol Chem 272: 26117–26124, 1997). In this study, we assessed the significance of our previous finding by perfusing hearts with long-chain fatty acids and tested the effects of changes in O2 supply. We showed that under all of these conditions citrate was enriched in an isotopomer containing five 13C atoms. This isotopomer can only be explained by substrate flux through reversal of the NADP+-ICDH reaction, which is evaluated at 3–7% of flux through citrate synthase. Small variations in reversal fluxes induced by low-flow ischemia that mimicked hibernation occurred despite major changes in contractile function and O2 consumption of the heart as well as citrate and succinate release rates and tissue levels. Our data show a reverse flux through NADP+-ICDH and support its hypothesized role in the fine regulation of CAC activity in the normoxic and O2-deprived heart.

Cardioprotective effects of KRN2391 and nicorandil on ischemic dysfunction in perfused rat heart

1991 ◽  
Vol 204 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Ohta Hideo ◽  
Jinno Yasuhiro ◽  
Harada Katsuhiko ◽  
Ogawa Nobuyuki ◽  
Fukushima Hideaki ◽  
...  
Keyword(s):  
Rat Heart ◽  
Perfused Rat Heart ◽  
Cardioprotective Effects

A critical perspective of the use of 13C-isotopomer analysis by GCMS and NMR as applied to cardiac metabolism

2004 ◽  
Vol 6 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Christine Des Rosiers ◽  
Steven Lloyd ◽  
Blandine Comte ◽  
John C Chatham
Keyword(s):  
Cardiac Metabolism ◽  
Critical Perspective ◽  
Isotopomer Analysis ◽  
13C Isotopomer Analysis

Decreased Susceptibility of Contractile Function to Hypoxia/Reoxygenation in Chronic Infarcted Rat Hearts

1998 ◽  
Vol 30 (11) ◽  
pp. 2341-2353 ◽  
Author(s):  
K.D. Wagner ◽  
D. Geil ◽  
I. Schimke ◽  
H.M. Stauss ◽  
A. Lammerich ◽  
...  
Keyword(s):  
Contractile Function ◽  
Rat Hearts ◽  
Hypoxia Reoxygenation

Mass isotopomer study of the nonoxidative pathways of the pentose cycle with [1,2-13C2]glucose

1998 ◽  
Vol 274 (5) ◽  
pp. E843-E851 ◽  
Author(s):  
Wai-Nang Paul Lee ◽  
Laszlo G. Boros ◽  
Joaquim Puigjaner ◽  
Sara Bassilian ◽  
Shu Lim ◽  
...  
Keyword(s):  
Pentose Phosphate ◽  
Gas Chromatography Mass Spectrometry ◽  
Hep G2 ◽  
Tracer Method ◽  
Human Hepatoma Cells ◽  
Glucose Flux ◽  
Isotopomer Analysis ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Mass Isotopomer

We present a single-tracer method for the study of the pentose phosphate pathway (PPP) using [1,2-13C2]glucose and mass isotopomer analysis. The metabolism of [1,2-13C2]glucose by the glucose-6-phosphate dehydrogenase, transketolase (TK), and transaldolase (TA) reactions results in unique pentose and lactate isotopomers with either one or two13C substitutions. The distribution of these isotopomers was used to estimate parameters of the PPP using the model of Katz and Rognstad (J. Katz and R. Rognstad. Biochemistry 6: 2227–2247, 1967). Mass and position isotopomers of ribose, and lactate and palmitate (products from triose phosphate) from human hepatoma cells (Hep G2) incubated with 30% enriched [1,2-13C2]glucose were determined using gas chromatography-mass spectrometry. After 24–72 h incubation, 1.9% of lactate molecules in the medium contained one 13C substitution ( m 1) and 10% contained two 13C substitutions ( m 2). A similar m 1-to- m 2ratio was found in palmitate as expected. Pentose cycle (PC) activity determined from incubation with [1,2-13C2]glucose was 5.73 ± 0.52% of the glucose flux, which was identical to the value of PC (5.55 ± 0.73%) determined by separate incubations with [1-13C] and [6-13C]glucose.13C was found to be distributed in four ribose isotopomers ([1-13C]-, [5-13C]-, [1,2-13C2]-, and [4,5-13C2]ribose). The observed ribose isotopomer distribution was best matched with that provided from simulation by substituting 0.032 for TK and 0.85 for TA activity relative to glucose uptake into the model of Katz and Rognstad. The use of [1,2-13C2]glucose not only permits the determination of PC but also allows estimation of relative rates through the TK and TA reactions.

Losartan prevents contractile dysfunction in rat myocardium after left ventricular myocardial infarction

2001 ◽  
Vol 281 (5) ◽  
pp. H2150-H2158 ◽  
Author(s):  
Marcel C. G. Daniëls ◽  
Rebecca S. Keller ◽  
Pieter P. de Tombe
Keyword(s):  
Myocardial Infarction ◽  
Sarcomere Length ◽  
Contractile Function ◽  
Left Ventricular ◽  
Contractile Dysfunction ◽  
Treatment Results ◽  
Twitch Force ◽  
Rat Hearts ◽  
Myofilament Function ◽  
Active Peak

We studied the effects of chronic losartan (Los) treatment on contractile function of isolated right ventricular (RV) trabeculae from rat hearts 12 wk after left ventricular (LV) myocardial infarction (MI) had been induced by ligation of the left anterior descending artery at 4 wk of age. After recovery, one-half of the animals were started on Los treatment (MI+Los; 30 mg · kg−1 · day−1per os); the remaining animals were not treated (MI group). Rats without infarction or Los treatment served as controls (Con group). MI resulted in increases in LV and RV weight and unstressed LV cavity diameter; these were partially prevented by Los treatment. The active peak twitch force-sarcomere length relation was depressed in MI compared with either Con or MI+Los. Likewise, maximum Ca2+saturated twitch force was depressed in MI, whereas twitch relaxation and twitch duration were prolonged. Myofilament function, as measured in skinned trabeculae, was not significantly different among the Con, MI, and MI+Los groups. We conclude that Los prevents contractile dysfunction in rat RV trabeculae after LV MI. Our results suggest that the beneficiary effect of Los treatment results not from improved myofilament function but rather from improved myocyte Ca2+homeostasis.

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